Research Facility

In order to precisely compensate the contribution of temperature fluctuations to the output voltages of the split film under low wind speed condition, it is necessary to obtain precise calibration data under stable wind speed and temperature conditions. A calibrator for a hot-wire anemometry and a cold-wire thermometer, as shown in Figure 1, is used to improve the calibration precision and efficiency.

In this calibrator, a laminar flow-meter measures the flow volume rate inside the calibrator (diameter: D = 100 nm), and the cross-sectional mean wind speed Umean is obtained by dividing the flow volume rate by the area of cross section at the measurement point. Based on this Umean and the wind speed distribution, calibrated wind speed Uc (wind speed at the center of the calibrator) is obtained. For temperature control inside the calibrator, a duct heater is used, and the air temperature θa inside the calibrator is measured by a thermocouple with a wire diameter of 75 μm. Here, heat insulating material is used for outer package, to reduce the influence of the air temperature outside the calibrator. If a hot wire and a cold wire are placed around the center of the calibrator, the influence of error on calibration precision is extremely small.

Figure 1. Sketch of calibrator for hot-wire and cold-wire

Photo 1. Overview of calibrator		Photo 2. Probes of temperature probe and velocity sensors